1. Field of the Invention
The present invention relates to a microphone for transmitting an input sound signal by the use of infrared rays, and also to a microphone system employing such a microphone therein.
2. Description of the Prior Art
It is generally noted of late that vocal and hand microphones are utilized in remarkably wide fields inclusive of public performances, lectures, conferences, karaoke (entertainment of singing songs over a prerecorded backing tape) and so forth. In the customary use of such microphone, there may arise, depending on individual situation, a problem of limitation in the user's action area due to the existence of cords for transmitting an input sound signal to an amplifier, a mixer and so on, and some more inconvenience is unavoidable with regard to entanglement of the cords. In view of the condition mentioned, there are known wireless type microphones which employ FM waves for eliminating the above drawbacks.
However, any wireless microphone using FM waves is permitted to output merely feeble waves because of the restriction by the Radio Regulation Law, so that the practically usable area is considerably limited. There is further needed an apparatus to receive the FM waves transmitted from the microphone and, since the transmitted signal is so feeble, the apparatus is required to have a high reception sensitivity. Due to such requirements, the apparatus is rendered considerably expensive, and therefore some difficulties are unavoidable in the operation of the above system by general users.
In addition, due to transmission of a sound signal by radio waves, the audio content naturally propagates also to the outside of the room where the microphone is used. For this reason, it is not exactly suited for use in a conference or the like where secrecy needs to be strictly observed, hence further limiting the usable area.